OK, you've got a corrupt stage 3 bootloader.

If you successfully backed up the old version before this one got corrupted, you can try to recover by simply loading up the backup image. To do that, please try the following...
from sff7000 prompt enter the following...

fatls mmc 1
this will dump the contents of your boot partition. from here, you should be able to find the backup file, for this example, I'll assume you named the file u-boot-octeon_rhino_itus7x.bak

setenv octeon_stage3_bootloader u-boot-octeon_rhino_itus7x.bak
bootstage3

If the backup bootloader is hosed then to fix it you'll need to set up a TFTP server.

Download bootloader v1.4 from share drive, put it in tftp folder
u-boot-octeon_rhino_itus7x.bin

from sff7000 prompt, enter the following

dhcp 
make sure shield is attached to network and can receive a DHCP address.
entering this command will initialize ethernet & request an address.

setenv serverip x.x.x.x
where x.x.x.x is the IP address of your tftp server

tftp u-boot-octeon_rhino_itus7x.bin
bootstage3


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Once you get back into linux, you'll want to mount your boot partition to overlay then copy the backup file over the corrupted one then restart. if successful you'll have downgraded to an old working bootloader and should now be able to boot into linux to try upgrading again.

so...

mount /dev/mmcblk0p1 /overlay
cd /overlay
cp u-boot-octeon_rhino_itus7x.bak u-boot-octeon_rhino_itus7x.bin
cd ..
umount /overlay

reboot -f